The invention relates to a portable power tool of the type having a rotating output shaft provided with an anti-vibration balancing device in the form of a ball type balancing unit for dampening unbalance in a working implement connected to the output shaft.
In the prior art there are known power tools, such as disclosed in U.S. Pat. No. 5,839,950, which are provided with a ball type balancing unit carried at the forward end of the output shaft so as to accomplish an automatic balancing of the vibration forces generated by a grinding wheel attached to the output shaft. By such an arrangement there is obtained a static balancing only, and since there is an inevitable axial distance between the grinding wheel and the balancing unit there will still be dynamic forces causing vibrations with respect to an axis of inertia of the tool. These vibrations can cause an uncomfortable and sometimes a detrimental working situation for the tool operator.
It is a primary object of the invention to accomplish a portable power tool of the above type in which the static as well as the dynamic vibration forces are counteracted such that the working situation for the operator is improved.
Further objects and advantages of the invention will appear from the following specification and claims.